The present invention relates to an optical pickup apparatus for recording and reproducing information by irradiating a laser beam onto an optical information recording medium such as an optical disk, an optically magnetic disk, etc.
In an optical pickup apparatus, when a carriage is moved in a seeking direction, an optical axis is shifted by the rotation of the carriage around the Y-axis and the Z-axis as well as the X-axis. Here, the optical axis shift caused by the rotation of the carriage around the Z-axis will especially be described.
The carriage is moved on a guide rail so that the carriage is assumed to be rotated by a certain angle around the Z-axis in inner and outer circumferential sections of an optical disk. In this case, a deflecting prism is also rotated by this angle. Accordingly, the incident optical axis with respect to the optical disk at the rotating time of the carriage is inclined by the above angle in comparison with the incident optical axis when the carriage is not rotated. Thus, the reflected light from the optical disk is shifted by a certain distance with respect to the incident optical axis.